1. Field of the Invention
This application relates generally to a semiconductor device.
2. Description of the Related Art
High-integration of integrated circuits using a semiconductor device, in particular, a MOS (Metal Oxide Semiconductor) transistor which is a field effect transistor having a gate electrode with a MOS structure is advancing. Together with advancement of high-integration, microfabrication of such MOS transistor used in the integrated circuit is progressed in the range of a nano order. When a MOS transistor configures an inverter circuit (NOT circuit) that is one of the basic circuits for digital circuits, if microfabrication of that MOS transistor advances, it becomes difficult to suppress any leak current, and the reliability is deteriorated because of a hot-carrier effect. Moreover, reduction of an occupy area of a circuit is not easily accomplished because of the necessity of ensuring a necessary current amount. In order to overcome such problems, there is proposed a Surrounding Gate Transistor (SGT) having an island semiconductor layer where a source, a gate, and a drain are arranged in the vertical direction relative to a substrate, and employing a structure that the island semiconductor layer is surrounded by a gate, and there are also proposed CMOS inverter circuits using such SGT (see, S. Watanabe, K. Tsuchida, D. Takashima, Y. Oowaki, A. Nitayama, K. Hieda, H. Takato, K. Sunouchi, F. Horiguchi, K. Ohuchi, F. Masuoka, H. Hara, “A Nobel Circuit Technology with Surrounding Gate Transistors (SGT's) for Ultra High Density DRAM's”, IEEE JSSC, Vol. 30, No. 9, 1995). Size reduction can be accomplished by such CMOS inverter circuit using the SGT, but further size reduction of the CMOS inverter circuits using the SGT is desired.
The present invention has been made in view of the foregoing circumstances, and it is an object of the present invention to provide a semiconductor device which has a CMOS inverter circuit with an SGT and which accomplishes high-integration.